1. Field of the Invention
The present invention relates generally to a preassembled pressure relief apparatus, and more particularly, but not by way of limitation, to an improved preassembled pressure relief apparatus of the rupturable type adapted to be clamped between conventional pipe flanges.
2. Description of the Prior Art
A variety of pressure relief apparatus of the rupture disk type have been developed. Generally, such apparatus include a rupture disk supported between a pair of special flanges which are in turn welded or otherwise connected in a pressure system or to a pressure vessel. When the pressure level within the system or vessel exceeds the design rupture pressure of the disk, the disk ruptures so that excess fluid pressure is relieved.
Recently, pressure relief devices of the rupturable type have been developed for clamping between conventional pipe flanges. That is, instead of special flanges which are relatively expensive, a pair of supporting members adapted to be clamped between conventional pipe flanges are provided, between which the rupture disk is held. This type of apparatus has also taken various forms, i.e., in one form the supporting members are of a reduced size such that they fit between the bolt members of the pipe flanges and are held together prior to installation with light side-mounted bars or other means. Other forms of such apparatus include supporting members of full size, i.e., a size corresponding with the diameter of the pipe flanges and include openings through which the bolt members of the pipe flanges are passed. Certain of the prior full diameter apparatus include cap screws disposed therein whereby the supporting members and rupture disk are preassembled and clamped together prior to installation between the pipe flanges.
In use of the prior apparatus of reduced diameter which fits between the bolt members of the pipe flanges, problems have been encountered due to misalignment of the rupture disk within the supporting members, misalignment of the supporting members with each other and the application of too much, too little or imbalanced load on the rupture disk resulting in improper operation of the rupture disk, i.e., raising or lowering the design rupture pressure of the disk. Also, such apparatus cannot be removed and inspected and then placed back in service without running the risk of impairing the operation of the rupture disk in that upon clamping the disk a second time between the supporting members, distortion of the disk may result, thereby raising or lowering the rupture pressure thereof. While the prior preassembled full diameter apparatus have generally overcome the problems associated with misalignment, etc., mentioned above, in order to remove the apparatus for inspection, all of the bolt members of the pipe flanges must be removed.
Attempts to utilize preassembled apparatus having circular supporting members of reduced diameter whereby the apparatus fits between the bolt members of the pipe flanges have been largely unsuccessful, particularly in low pressure applications, due to the requirement that the means for clamping the supporting members and rupture member together in preassembly, i.e., cap screws or the like, must be positioned in the area forming the seating surfaces of the supporting members which coact with the seating surfaces of the pipe flanges thereby interfering with the ability of the apparatus to seal against the seating surfaces of the pipe flanges.
By the present invention, an improved preassembled pressure relief apparatus adapted to be clamped between conventional pipe flanges is provided which avoids the problems associated with misalignment, etc., mentioned above, and which can be readily removed for inspection and reinstalled without the necessity of removing all of the bolt members of the pipe flanges. Further, a single apparatus of the present invention can be utilized with conventional pipe flanges of various pressure ratings.